This amino acid is necessary for efficient fatty acid metabolism, which results in cellular energy production (in other words this amino acid is needed to help turn fat into energy). Athletes commonly take this amino acid to improve energy levels to achieve optimum exercise performance; however, individuals with chronic fatigue may also find this amino acid helpful for increasing energy levels. Since fatty acids are the primary fuel for energy production in the heart muscle, normal heart function depends on sufficient levels of this amino acid. In addition, newer studies reveal that this amino acid can help maintain healthy cholesterol and blood lipid levels. What is this amino acid?